Stingrays, scallops and scapegoats

Certain stingrays that are found in subtropical and temperate waters around the world have an ability shared by few other marine fish: to crush through the protective shells of creatures like clams, oysters, scallops and snails, and eat them. These rays, which include eagle and cownose rays, are durophagous, or ‘hard-eating’ – a word used to describe any animal that consumes hard food, like the hyena with its bone-crushing eating habits.

But the shell-encased food that durophagous stingrays are after is not only essential to the rays; it’s also desired by humans. Because they eat shellfish that are economically valuable to fishers (think scallops and oysters), the hard-eating stingrays are often considered pests, and they have been blamed for preventing the recovery of shellfish in parts of their range. This has led to ‘kill tournaments’, culling and campaigns to promote eating them – all aimed at reducing their numbers, even though these marine fish are among the slowest at reproducing and there is minimal evidence to support their bad reputation. It is within this context that Matt Ajemian, an assistant research scientist at the Harte Research Institute for Gulf of Mexico Studies, dedicated seven years of research to understanding the effects of durophagous stingrays on shellfish. In 2013, with the support of the Save Our Seas Foundation, Matt organised a symposium at the annual American Elasmobranch Society meeting to collate scientists’ knowledge of these misunderstood rays. The result was published in September 2014. The symposium also provided an opportunity for the participants to draft a science-based conservation plan in response to the rapidly growing fishery for cownose rays along the US Atlantic coast.

To date, few studies have shown that durophagous rays have a negative effect on shellfish resources. Matt hopes to change the perception of rays as scapegoats for the declines in shell-fish and to ensure that they are managed in a sustainable way.